The present invention relates to an improved silicon steel sheet and particularly a silicon steel sheet with a changed soldering structure to facilitate production of silicon steel cores to reduce costs and increase production yield.
Most presently known current limiters or choke coils have a silicon steel core formed in an annular shape (as shown in FIGS. 1A and 1B). Th silicon steel core is made of an elongated silicon steel sheet cut to a selected length from a silicon sheet 10. The formed silicon steel sheet has two lateral ends 10a and 10b. Then anchor one lateral end 10b to wind the silicon steel sheet in an annular shape by means of a tool to form the silicon steel core desired, and solder another lateral end 10a at a solder spot 10c. The silicon steel core thus made usually has two corners 10d at the lateral end 10a that are prone to turn upwards. The turned corners tend to hamper installation of the silicon steel core into the casing and make assembly more difficult. Moreover, the corners 10d tend to become very sharp after being cut. Workers who do assembly or installation of the silicon steel cores in the casings could easily get hurt or injured. While fully soldering the lateral end 10a and corners 10d can eliminate the turning up problem of the corners 10d, it causes additional problems in soldering operation and results in higher costs.
There are many techniques disclosed in the prior art to address the product winding processes. References can be found in U.S. Pat. Nos. 5,813,616, 2,094,454, 2,191,028, 2,776,094, 3,583,558 and 4,445,646. They generally propose to cut the end of the winding articles to a triangular shape to facilitate winding operations. Those techniques mostly aim to winding soft materials such as photo films, plastic rolls, paper, etc. The technique for winding stiff material such as silicon steel sheet is still unknown.
The primary object of the invention is to resolve aforesaid disadvantages. The invention provides a novel silicon soldering structure to allow the cut lateral ends fastening to the silicon steel sheet securely.
Another object of the invention is to provide an annular silicon steel core structure that is easier to make to reduce costs and increase production yield.
A further object of the invention is to protect workers from injury during producing and assembling the silicon steel cores.
To achieve the foregoing objects, the silicon steel sheet of the invention has two lateral ends after being punched. Each lateral end has a side edge which is narrower than the original width of the silicon steel sheet. Between the side edge and the lateral sides of the silicon steel sheet, two slant solder zones are formed for soldering use at the initial winding stage and the final winding stage.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.